Field of the Invention
The invention generally relates to compositions and methods for promoting hemostasis. In particular, the invention provides compositions comprising clay minerals, which, when applied to a bleeding area, function to 1) absorb liquid and 2) promote blood clotting.
Background of the Invention
Hemorrhagic events, from the minor to the life threatening, result from a wide variety of circumstances and occur in a wide variety of settings. The conditions which result in hemorrhage may be relatively predictable, such as those associated with medical procedures. Alternatively, hemorrhagic events may result from unpredictable circumstances, such as a breach of the skin or an internal organ in an accident. Such acute traumatic wounds occur in an almost infinite number of patterns and degrees, making the use of simple compression or application of a single type of bandage, impractical if not impossible, especially in the most severe circumstances. For example, a traumatic wound to the groin cannot be readily controlled either by simple direct pressure or by the use of a simple flat bandage.
Attempts have been made which partially address the treatment of hemostasis, and/or the need for flexibility in wound dressings:
1) Hemcon's Chitosan Bandage (see the website located at hemcon.com) is a gauze bandage impregnated with chitosan. Chitosan, a fiber derived from chitin in shellfish, is a nondigestible aminopolysaccharide. Chitosan is synthesized by removing acetyl groups from chitin, through a process called deacetylation. Chitosan is known to have significant coagulant properties which are believed to be based on its cationic (positive charge) properties. However, its mucoadhesive properties may also be responsible. In models of life threatening hemorrhage (J Trauma 2005; 59:865-875 and J Trauma 2004; 56:974-983), the ability of the bandage to improve survival has been limited. In one study, use of the bandage had a 100% failure rate (isolated arterial injury). In a second study (combined arterial and venous hemorrhage at low blood pressures) the bandage resulted in a 28% mortality rate. It was noted that there was a bandage-to-bandage variability in performance and ability of the bandage to adhere to the wound. This bandage is available in only one size and formulation. The ability to produce a powder or granular form of chitosan similar to that of QuickClot or the bentonite clay described in this application is likely to be limited. Powdered chitosan does not mix well with blood.2) The Fibrin Sealant Dressing (FSD) is the result of a collaborative effort between the U.S. Army and the American Red Cross. It is made from fibrin, thrombin, and factor XIII purified from human donated blood and plasma. It is thus a biologic which has a potential for disease transmission even though this risk is small. The FSD controls hemorrhage by promoting natural clot formation at the site of injury since it provides concentrated coagulation factors at the site of injury. However, it is a biologic and the manufacture of such bandages is extremely labor-intensive, and their cost may prohibit routine use in most circumstances (estimated cost between $500 and $1000). The dressings are fragile and tend to break apart if not carefully handled. In a study performed by the U.S. Army (J Trauma 2005; 59:865-875) utilizing a model of severe arterial bleeding, the FSD bandage significantly improved survival when compared with the Army Field dressing, QuickClot and the HemCon bandage. The product comes only in bandage form.3) The Rapid Deployable Hemostat (RDH) is a bandage made by Marine Polymer Technologies and incorporates a derivative from sea algae to promote hemostasis. However, in a study by Alam and colleagues (Alam, et al. J Trauma 2003; 54:1077-1082), which explored the ability of many commercial products to stop severe bleeding and to increase survival, use of the RDH resulted in lower survival rates than a simple standard bandage. This would indicate that the current components of the RDH are not suitable for use in life threatening hemorrhage. Furthermore, to our knowledge, this product's only available form is one of a bandage. The cost of this product may be expensive and is currently estimated to be approximately $300 per unit.4) U.S. Pat. No. 4,748,978 (to Kamp) discloses a therapeutic dressing that includes a flexible permeable support and a mixture of mineral components, including bentonite, kaolinite and illite or attapulgite, and may include anti-fungal (or other) agents as well. The dressing is reported to be designed to be flexible and to be able to be made or cut to any desired size. It is reported to be intended primarily to treat burns, but can also be used for the treatment of ulcers. However, the dressing is not described as suitable for the treatment of hemorrhage, and no data from Kamp is available to support its use for this indication.5) U.S. Pat. No. 4,822,349 (to Hursey et al.) describes a non-bandage material used to treat bleeding. The material is sold by Z-Medica as “Quick-Clot” (see the website located at z-medica.com) and is a granular form of zeolite, an aluminum silicate mineral. During use, it is poured into a wound. In addition to absorbing water from hemorrhaged blood and concentrating hemostatic factors in the blood at the site of injury, its mechanism of action appears to involve chemical cautery. An intense exothermic reaction is produced upon contact with liquid (e.g. blood), and is likely responsible for stoppage of blood flow by cauterization. While use of this material may be preferable to bleeding to death, the attendant burning of tissue at and near the wound (and possible burn injury of medial personnel who are administering the material) is clearly a severe disadvantage. This side effect also reduces the ability of the material to be used for internal hemorrhage. While the manufacturer indicates that the main mechanism of action is the superaborbant nature of zeolite which absorbs water out of blood to concentrate clotting factors, the patent (U.S. Pat. No. 4,822,349 (to Hursey et al.) indicates that its action lies mainly through the exothermic reaction it creates. Studies by Alam and colleagues (J Trauma 2004; 56:974-983) clearly demonstrate that the ability of this product to stop hemorrhage is quickly lost when it is partially hydrated in attempts to reduce the exothermic reaction and the resulting temperature it produces in tissues. When the granules are placed in a bag similar to a tea bag to facilitate removal, its ability to stop bleeding is significantly limited. In addition, to our knowledge this product has not been made into a bandage and even if it were it would likely still produce a significant exothermic reaction upon contact with blood.6) A product made by TraumaDex (see the website located at traumadex.com) is also a non-bandage. In this case, the product is a powder consisting of microporous beads which absorb water and which contain concentrated clotting factors. During use, the material is poured or squirted into the wound. However, when studied by Alam and colleagues (J Trauma 2003; 54:1077-1082) in a model of severe hemorrhagic shock, TraumaDex performed no better than a standard field dressing, thus offering no advantage and certainly more expense. Alam and colleagues studied this product again (J Trauma 2004; 56:974-983) and demonstrated its performance to be suboptimal compared to QuickClot and the Hemcon bandage. In this study; it performed only slightly better than a standard dressing. Also to our knowledge, this product has not been made into a bandage and even if it were it would probably lack efficacy in stopping severe bleeding.
A “one size fits all” approach to the treatment of hemorrhage clearly does not and cannot work, and the prior art has thus far failed to provide compositions and methods to treat hemorrhage that are inexpensive, efficacious, highly adaptable, easy to use, and lacking in serious side effects.